Die structure



Jam 7, WM. H. MRTCHELL DIE STRUCTURE Filed Dec. 5, 1938 flsATTORNPatented Jan. 7, 1941 UNITED STATES PATENT OFFICE on: smoc'romz DelawareApplication December 5, 1938, Serial No. 243,959

3 Claims. 10-24) This invention relates to improvements in dies for usein heading machines of the type adapted to make headed screws, rivets,nails and the like, a particular object being the provision of a diewhich is simple in construction and requires less material than dies ofthe same class made y the old methods, the improved die having aconsiderably longer life than the old dies and making a. uniform productfor a greater number of i0 operations.

Another important object is the provision of improved seating means formounting a die in a heading machine or other utilization means toeliminate the danger of splitting and other in- 18 juries where the dieis subjected to great pressure.

Another object is the provision of a die of novel constructioncomprising a die core and a holder therefor and characterized by thefact that the 20 core may be of reduced size and bulk compared to theholder, the reduced size making it possible to temper or harden the coremore uniformly throughout the entire mass thereof than was possible inthe older type of die.

26 Viewed from another aspect, it is an important object of theinvention to provide a die consisting of a bushing adapted to fit into adie holder or seat, said bushing being split in an axial direction alongone side thereof and having fill secured in its bore a die plug ofsubstantially less bulk than the bushing and highly tempered, thebushing making it possible to employ a die plug of relatively small massand thus making it possible to thoroughly temper the plug.

355 Still another important object is the provision of a bushing havingouter peripheral portions tapered for reception in a tapered seat,pressure being applied at one end of the plug corresponding to thelarger end of the bushing so ll that the latter is wedged into the seatproportionately to the pressure applied, so that the die plug willlikewise be proportionately gripped by the bushing.

Other objects, advantages, economies, and

45 novel aspects of the invention reside in certain details ofconstruction and operation of the parts of the preferred embodiment, allof which will be made to appear as the following description proceeds inview of the annexed drawing, in

50 which:

Fig. 1 is a perspective view of a die bed in a heading machine with thenovel die seated in operative position;

Fig. 2 is a cross section along line 2.--2 of 55 Fig. 1, scale beingslightly nlarged;

Fig. 3 is a cross section through thedie along line 3-3 of Fig. 2 and toslightly enlarged scale;

Fig. 4 is a perspective view of the split bush+ ing; while Fig. 5 is aperspective view of one form of die 5 plug. v

Extruding and heading machines commonly employ a die holder or'bed inwhich a die plug is removably mounted to have pressure applied againstthe exposed end thereof to form or deform stock which is fed intoposition before the die or into the die, in cooperation with pressuremeans, usually some form of plunger. Dies made in accordance with themethods heretofore known have been unsatisfactory because their life islimited due principally to the fact that they cannot be tempered bypractical industrial methods to a degree of hardness which willwithstand the tremendous pressure applied thereto for any great lengthof time. In order to give these dies 9, maximum life, the bulk or massof a given die could not be reduced beyond a given point, or, stated inother terms, the size of a die for a given operation could not bereduced below a given dimension if the die were to stand up for anappreciable number of operations. In accordance with the former methods,these dies were first tooled and then tempered or hardened and becauseof their bulk, the tempering of the metal was not uniform throughout itsmass, the dies being harder around their marginal portions and softer indirections inwardly from the marginal portions into the body thereof. Asa consequence, such dies tend to split under repeated applications ofthe relatively enormous pressures necessary to extrude or deform metalstock engaged therewith.

The present invention overcomes the foregoing difiiculties and providesa die which elimi- 4o hates splitting, which is of simple constructionand which reduces the material required for the entire die assembly, andthus lowers costs, and which moreover makes it possible to provide amore highly and uniformly tempered die which 5 will assure a uniformproduct over a longer period and for a greater number of operations ofthe forming machinery.

In one of its preferred forms, the improved die includes a chuck orholder in the form of a metal sleeve l0 (Fig. 4) which is tapered fromone end Illa inwardly toward its opposite end it?) on the outerperiphery thereof. The chuck or holder is split as at H in an axialdirection from the end llla toward the end Nb so that the bore l2 may besaid to be somewhat expanslble.

The die proper includes an insert or plug l5 (Fig. 5) which in thisinstance is provided with 5 a bore l6 throughout its length (Figs. 2 and3 also), the axial ends of the plug in this instance being countersunkas at I! to provide a heading formation for the manufacture of a fiathead rivet or screw or analogous device from rod- 10 like stock l8 whichis fed into the outer end of the plug (as illustrated in dotted lines inFig. 1). The die insert or plug is dimensioned to fit snugly into thebore I2 of the chuck or holder It) as shown in Figs. 2 and 3, theopposite ends 15 of the plug being flush with the extremities Illa and"lb of the chuck. With the parts l and I thus assembled, the forming dieis complete and ready for insertion in the die bed or seat.

The invention further contemplates an im- 20 proved seating means forsuch dies, such a means comprising: as viewed particularly in Fig. 2, aseating block 20 which may be variously shaped to fit into the die bedor holder in various heading or extruding machines, opposite sideportions 25 2t and 22 of the block being beveled or sloped to fit intoa. bed 23 in the forming machine, this bed including a keying block 24secured in place by a locking nut 25 against the side 2i of the seatingblock to hold the latter immovably in 80 the bed.

The seating block 20 is provided with a bore 28 tapered to receive thechuck or holder it of the die so that the outer end portion Illa thereofwill lie fiush with the outer face of the block 29.

35 In the operation of the forming machine chosen for illustrativepurposes herein, there is a. stock feeding channel 32 leading from thebed 23 into register with a feeding sleeve 3! also removably secured inthe seating block 20, 40 rodlike stock such as the blank l8 being fedautomatically by mechanism not illustrated herein, so that apredetermined length of stock issued from the outer end of the feedingsleeve 3i and is automatically cut off by a shear 32 moving 45 acrossthe opening of the feeding sleeve, the

shear being provided with holding means 33 wherein the sheared blank issecured by a springurged finger 34 (Fig. 1) while the shear cone tinuesmovement toward the die to align the 50 blank with the bore I6 of thedie insert. When thus aligned, the blank I8 is moved into the bore l6 bytimed movement of a plunger 35.

The blank is backed in the die by a combina tion backing and kick-outrod 36 (Fig. 2) which 55 is urged by a plunger 31 into the bore I6 ofthe die against the innermost end of the blank in properly timedrelation to the movement of the heading plunger 35 so that the outermostend portion of the blank is forced into the tapered or 0 enlarged endportion l1 and constitutes a fiat head on a rivet or screw, the knifeand holding means meanwhile having been withdrawn from the path of theplunger 35 and the latter withdrawing afterformation of the article, andthe 65 knock-out plunger 31 thereafter moving forward (to the right) toeject the headed screw or rivet from the die, whereupon the machine isready forthe next cycle of operation.

Due to the taper of the bushing or die holder and the correspondingtaper of the seating block 20, the increase in gripping pressure of thebushing on the die insert l5 may be said to be substantiallyproportionate to the pressure applied 5 by the plunger 35 and is at alltimes adequate to secure the die in exactly alignedposition, the dieholder in nevertheless being readily removed from its seat 20 when it isto be replaced by a different die. The gripping pressures exerted uponthe insert by the bushing or holder are substantially uniformlydistributed and this, coupled with the fact that the improved dieconstruction makes possible a complete and effective tempering of theinsert, results in a die of exceptional durability and one which willhold its tolerances for a considerably greater number of operationsthanthe old type of die.

The objects and advantages of the invention may be realized in modifiedforms of construction, and the invention is therefore not to berestricted to any of the precise details recited herein in describing anillustrative embodiment thereof except as may be provided in theappended claims.

Having thus described my invention, what I claim as new and desired toprotect by Letters Patent is:

1. A heading die including a holder in the form of a tubular bushingwhich is split along one side throughout its length, and a tempered dieinsert of cylindrical form and minimized cross sectional thicknesssumcient to facilitate uniform tempering fitted into the tubular portionof said holder, the latter being adapted normally to grip said insertand hold the same securely in place, the slotted formation of the holderproviding yieldability thereof in a circumferential sense for removal ofthe insert.

2. A heading die including a holder of sub- 40 stantially tubular formsplit along one side throughout its length and having a die insert ofminimized cross section to facilitate tempering, said insert beinghighly tempered and fitted intothe bore thereof, said holder havingouter peripheral portions tapered from one end toward the other to fitinto a correspondingly tapered die seat, pressure being applied to saidinsert at the larger end of said holder so that the latter will beforced into said seat, the split formation of 60 the holder permittingthe same to be tightly contracted about said insert to hold the latteragainst substantial movement during application of pressure thereto.

3. .A tempered heading die for use in a. conical- 1y tapered seat, saiddie comprising a holding sleeve having a cylindrical bore and conicallytapered outer wall portions adapted to fit into said seat, said sleevebeing slit longitudinally to permit expansion and contraction acrosssaid bore, and a tempered cylindrical die insert having an optimumminimized cross-sectional thickness rendering the same permeable totempering and hardening agencies throughout a major part of its bulk,said insert fitting into said bore in the holder and being reinforcedand held by the latter when operatively disposed in said seat.

HARVEY MITCHELL.

